bootp/dhcp6: DHCPv4/v6 ZTP and SZTP option support

DHCPv4: RFC8572 specifies the SZTP redirect tag.

DHCPv6: RFC5970 specifies the boot file URL, used for ZTP,
 and RFC8572 specifies the SZTP redirect tag
 The base DHCPv6 RFC3315 specifies the user class option.

6 files changed, 158 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index 0a86c125..91e087e2 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,9 @@
 DayOfTheWeek, Month DD, YYYY / The Tcpdump Group
   Summary for 5.0.0 tcpdump release (so far!)
     Refine protocol decoding for:
+      DHCP: parse the SZTP redirect tag
+      DHCP6: parse the user class, boot file URL, and SZTP redirect
+          options
       OpenFlow 1.0: Fix indentation of PORT_MOD, improve handling of
           some lengths, and fix handling of snapend.
       RIP: Make a couple trivial protocol updates.
diff --git a/print-bootp.c b/print-bootp.c
index d5418d97..227ed410 100644
--- a/print-bootp.c
+++ b/print-bootp.c
@@ -194,6 +194,8 @@ struct bootp {
 /* RFC 3442 */
 #define TAG_CLASSLESS_STATIC_RT	((uint8_t) 121)
 #define TAG_CLASSLESS_STA_RT_MS	((uint8_t) 249)
+/* RFC8572 */
+#define TAG_SZTP_REDIRECT	((uint8_t) 143)
 /* RFC 5859 - TFTP Server Address Option for DHCPv4 */
 #define	TAG_TFTP_SERVER_ADDRESS	((uint8_t) 150)
 /* https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml */
@@ -506,6 +508,8 @@ static const struct tok tag2str[] = {
 /* RFC 3442 */
 	{ TAG_CLASSLESS_STATIC_RT, "$Classless-Static-Route" },
 	{ TAG_CLASSLESS_STA_RT_MS, "$Classless-Static-Route-Microsoft" },
+/* RFC 8572 */
+	{ TAG_SZTP_REDIRECT,	"$SZTP-Redirect" },
 /* RFC 5859 - TFTP Server Address Option for DHCPv4 */
 	{ TAG_TFTP_SERVER_ADDRESS, "iTFTP-Server-Address" },
 /* https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml#options */
@@ -993,6 +997,39 @@ rfc1048_print(netdissect_options *ndo,
 				break;
 			    }
 
+
+			case TAG_SZTP_REDIRECT:
+				/* as per https://datatracker.ietf.org/doc/html/rfc8572#section-8.3
+				 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
+				 |        uri-length             |          URI                  |
+				 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
+
+				 * uri-length: 2 octets long; specifies the length of the URI data.
+				 * URI: URI of the SZTP bootstrap server.
+				 */
+				while (len >= 2) {
+					suboptlen = GET_BE_U_2(bp);
+					bp += 2;
+					len -= 2;
+					ND_PRINT("\n\t	    ");
+					ND_PRINT("length %u: ", suboptlen);
+					if (len < suboptlen) {
+						ND_PRINT("length goes past end of option");
+						bp += len;
+						len = 0;
+						break;
+					}
+					ND_PRINT("\"");
+					nd_printjn(ndo, bp, suboptlen);
+					ND_PRINT("\"");
+					len -= suboptlen;
+					bp += suboptlen;
+				}
+				if (len != 0) {
+					ND_PRINT("[ERROR: length < 2 bytes]");
+				}
+				break;
+
 			default:
 				ND_PRINT("[unknown special tag %u, size %u]",
 					  tag, len);
diff --git a/print-dhcp6.c b/print-dhcp6.c
index 6b0dc213..7e7d1246 100644
--- a/print-dhcp6.c
+++ b/print-dhcp6.c
@@ -188,8 +188,10 @@ struct dhcp6_relay {
 #  define DH6OPT_NTP_SUBOPTION_SRV_ADDR 1
 #  define DH6OPT_NTP_SUBOPTION_MC_ADDR 2
 #  define DH6OPT_NTP_SUBOPTION_SRV_FQDN 3
+#define DH6OPT_BOOTFILE_URL 59    /* RFC5970 */
 #define DH6OPT_AFTR_NAME 64
 #define DH6OPT_MUDURL 112
+#define DH6OPT_SZTP_REDIRECT 136  /* RFC8572 */
 
 static const struct tok dh6opt_str[] = {
 	{ DH6OPT_CLIENTID,           "client-ID"            },
@@ -239,8 +241,10 @@ static const struct tok dh6opt_str[] = {
 	{ DH6OPT_LQ_RELAY_DATA,      "LQ-relay-data"        },
 	{ DH6OPT_LQ_CLIENT_LINK,     "LQ-client-link"       },
 	{ DH6OPT_NTP_SERVER,         "NTP-server"           },
+	{ DH6OPT_BOOTFILE_URL,       "Bootfile-URL"         },
 	{ DH6OPT_AFTR_NAME,          "AFTR-Name"            },
 	{ DH6OPT_MUDURL,             "MUD-URL"              },
+	{ DH6OPT_SZTP_REDIRECT,      "SZTP-redirect"        },
 	{ 0, NULL }
 };
 
@@ -290,6 +294,8 @@ dhcp6opt_print(netdissect_options *ndo,
 	uint16_t subopt_len;
 	uint8_t dh6_reconf_type;
 	uint8_t dh6_lq_query_type;
+	u_int first_list_value;
+	uint16_t remainder_len;
 
 	if (cp == ep)
 		return;
@@ -784,6 +790,39 @@ dhcp6opt_print(netdissect_options *ndo,
 			ND_PRINT(")");
 			break;
 
+		case DH6OPT_BOOTFILE_URL:
+			tp = (const u_char *)(dh6o + 1);
+			ND_PRINT(" ");
+			nd_printjn(ndo, tp, optlen);
+			ND_PRINT(")");
+			break;
+
+		case DH6OPT_SZTP_REDIRECT:
+		case DH6OPT_USER_CLASS:
+			ND_PRINT(" ");
+			tp = (const u_char *)(dh6o + 1);
+			first_list_value = TRUE;
+			remainder_len = optlen;
+			while (remainder_len >= 2) {
+				if (first_list_value == FALSE) {
+					ND_PRINT(",");
+				}
+				first_list_value = FALSE;
+				subopt_len = GET_BE_U_2(tp);
+				if (subopt_len > remainder_len-2) {
+					break;
+				}
+				tp += 2;
+				nd_printjn(ndo, tp, subopt_len);
+				tp += subopt_len;
+				remainder_len -= (subopt_len+2);
+			}
+			if (remainder_len != 0 ) {
+				ND_PRINT(" ?");
+			}
+			ND_PRINT(")");
+			break;
+
 		default:
 			ND_PRINT(")");
 			break;
diff --git a/tests/TESTLIST b/tests/TESTLIST
index 1e115b6c..bdb88273 100644
--- a/tests/TESTLIST
+++ b/tests/TESTLIST
@@ -904,3 +904,6 @@ gquic				gquic.pcap			gquic.out	-v
 
 # GRE keepalives, CDP over GRE
 various_gre			various_gre.pcap		various_gre.out	-v
+
+# DHCP ZTP(RFC5970) and SZTP(RFC8572) tests
+dhcpv4v6-rfc5970-rfc8572        dhcpv4v6-rfc5970-rfc8572.pcap           dhcpv4v6-rfc5970-rfc8572.out    -vv
diff --git a/tests/dhcpv4v6-rfc5970-rfc8572.out b/tests/dhcpv4v6-rfc5970-rfc8572.out
new file mode 100644
index 00000000..bc0e8c6a
--- /dev/null
+++ b/tests/dhcpv4v6-rfc5970-rfc8572.out
@@ -0,0 +1,76 @@
+    1  13:35:23.334910 IP6 (flowlabel 0x03f85, hlim 1, next-header UDP (17) payload length: 80) fe80::200:1ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 solicit (xid=6aebe6 (vendor-specific-info) (client-ID hwaddr/time type 1 time 701530515 000001010000) (option-request SZTP-redirect DNS-search-list DNS-server) (elapsed-time 703) (IA_NA IAID:16842752 T1:3600 T2:5400))
+    2  13:35:45.614434 IP6 (flowlabel 0x03f85, hlim 1, next-header UDP (17) payload length: 80) fe80::200:1ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 solicit (xid=aca407 (vendor-specific-info) (client-ID hwaddr/time type 1 time 701530515 000001010000) (option-request SZTP-redirect DNS-search-list DNS-server) (elapsed-time 0) (IA_NA IAID:16842752 T1:3600 T2:5400))
+    3  13:35:45.618584 IP6 (flowlabel 0xe612c, hlim 64, next-header UDP (17) payload length: 281) fe80::cc0d:b4ff:fe8a:3384.547 > fe80::200:1ff:fe01:0.546: [udp sum ok] dhcp6 advertise (xid=aca407 (IA_NA IAID:16842752 T1:0 T2:0 (IA_ADDR 1234:5678::4 pltime:18000 vltime:28800)) (client-ID hwaddr/time type 1 time 701530515 000001010000) (server-ID hwaddr/time type 1 time 701530524 ce0db48a3384) (SZTP-redirect https://sztp1.download.com,https://sztp2.download.com:8080,https://10.10.0.0,https://10.10.0.0:8000,https://[2001:4860:4860::8888]:8080) (DNS-search-list aristanetworks.com.) (DNS-server 1234:5678::2))
+    4  13:35:46.635774 IP6 (flowlabel 0x03f85, hlim 1, next-header UDP (17) payload length: 126) fe80::200:1ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 request (xid=5f98e6 (vendor-specific-info) (client-ID hwaddr/time type 1 time 701530515 000001010000) (server-ID hwaddr/time type 1 time 701530524 ce0db48a3384) (option-request SZTP-redirect DNS-search-list DNS-server) (elapsed-time 0) (IA_NA IAID:16842752 T1:3600 T2:5400 (IA_ADDR 1234:5678::4 pltime:7200 vltime:7500)))
+    5  13:35:46.638223 IP6 (flowlabel 0xe612c, hlim 64, next-header UDP (17) payload length: 281) fe80::cc0d:b4ff:fe8a:3384.547 > fe80::200:1ff:fe01:0.546: [udp sum ok] dhcp6 reply (xid=5f98e6 (IA_NA IAID:16842752 T1:0 T2:0 (IA_ADDR 1234:5678::4 pltime:7200 vltime:28800)) (client-ID hwaddr/time type 1 time 701530515 000001010000) (server-ID hwaddr/time type 1 time 701530524 ce0db48a3384) (SZTP-redirect https://sztp1.download.com,https://sztp2.download.com:8080,https://10.10.0.0,https://10.10.0.0:8000,https://[2001:4860:4860::8888]:8080) (DNS-search-list aristanetworks.com.) (DNS-server 1234:5678::2))
+    6  13:56:39.000073 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
+    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from 00:00:44:01:00:00, length 300, xid 0x796a827d, Flags [none] (0x0000)
+	  Client-Ethernet-Address 00:00:44:01:00:00
+	  Vendor-rfc1048 Extensions
+	    Magic Cookie 0x63825363
+	    DHCP-Message (53), length 1: Discover
+	    Parameter-Request (55), length 10: 
+	      MTU (26), Subnet-Mask (1), BR (28), Default-Gateway (3)
+	      Domain-Name (15), Domain-Name-Server (6), LOG (7), Hostname (12)
+	      SZTP-Redirect (143), Classless-Static-Route (121)
+	    Vendor-Class (60), length 6: "Arista"
+	    Client-ID (61), length 6: "^@D^A^@^@"
+    7  13:56:40.003200 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 469)
+    10.10.0.2.67 > 10.10.0.4.68: [udp sum ok] BOOTP/DHCP, Reply, length 441, xid 0x796a827d, Flags [none] (0x0000)
+	  Your-IP 10.10.0.4
+	  Client-Ethernet-Address 00:00:44:01:00:00
+	  Vendor-rfc1048 Extensions
+	    Magic Cookie 0x63825363
+	    DHCP-Message (53), length 1: Offer
+	    Server-ID (54), length 4: 10.10.0.2
+	    Lease-Time (51), length 4: 28800
+	    MTU (26), length 2: 1500
+	    Subnet-Mask (1), length 4: 255.255.0.0
+	    Default-Gateway (3), length 4: 10.10.0.1
+	    Domain-Name (15), length 18: "aristanetworks.com"
+	    Domain-Name-Server (6), length 4: 10.10.0.1
+	    SZTP-Redirect (143), length 141: 
+		    length 26: "https://sztp1.download.com"
+		    length 31: "https://sztp2.download.com:8080"
+		    length 17: "https://10.10.0.0"
+		    length 22: "https://10.10.0.0:8000"
+		    length 35: "https://[2001:4860:4860::8888]:8080"
+    8  13:56:40.003500 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
+    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from 00:00:44:01:00:00, length 300, xid 0x796a827d, Flags [none] (0x0000)
+	  Client-Ethernet-Address 00:00:44:01:00:00
+	  Vendor-rfc1048 Extensions
+	    Magic Cookie 0x63825363
+	    DHCP-Message (53), length 1: Request
+	    Server-ID (54), length 4: 10.10.0.2
+	    Requested-IP (50), length 4: 10.10.0.4
+	    Parameter-Request (55), length 10: 
+	      MTU (26), Subnet-Mask (1), BR (28), Default-Gateway (3)
+	      Domain-Name (15), Domain-Name-Server (6), LOG (7), Hostname (12)
+	      SZTP-Redirect (143), Classless-Static-Route (121)
+	    Vendor-Class (60), length 6: "Arista"
+	    Client-ID (61), length 6: "^@D^A^@^@"
+    9  13:56:40.005894 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 469)
+    10.10.0.2.67 > 10.10.0.4.68: [udp sum ok] BOOTP/DHCP, Reply, length 441, xid 0x796a827d, Flags [none] (0x0000)
+	  Your-IP 10.10.0.4
+	  Client-Ethernet-Address 00:00:44:01:00:00
+	  Vendor-rfc1048 Extensions
+	    Magic Cookie 0x63825363
+	    DHCP-Message (53), length 1: ACK
+	    Server-ID (54), length 4: 10.10.0.2
+	    Lease-Time (51), length 4: 28800
+	    MTU (26), length 2: 1500
+	    Subnet-Mask (1), length 4: 255.255.0.0
+	    Default-Gateway (3), length 4: 10.10.0.1
+	    Domain-Name (15), length 18: "aristanetworks.com"
+	    Domain-Name-Server (6), length 4: 10.10.0.1
+	    SZTP-Redirect (143), length 141: 
+		    length 26: "https://sztp1.download.com"
+		    length 31: "https://sztp2.download.com:8080"
+		    length 17: "https://10.10.0.0"
+		    length 22: "https://10.10.0.0:8000"
+		    length 35: "https://[2001:4860:4860::8888]:8080"
+   10  14:15:10.112658 IP6 (flowlabel 0x03f85, hlim 1, next-header UDP (17) payload length: 80) fe80::200:1ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 solicit (xid=28792a (vendor-specific-info) (client-ID hwaddr/time type 1 time 701792102 000001010000) (option-request Bootfile-URL DNS-search-list DNS-server) (elapsed-time 754) (IA_NA IAID:16842752 T1:3600 T2:5400))
+   11  14:15:33.148466 IP6 (flowlabel 0x1570c, hlim 64, next-header UDP (17) payload length: 157) fe80::40d3:61ff:fe62:3810.547 > fe80::200:1ff:fe01:0.546: [udp sum ok] dhcp6 advertise (xid=654242 (IA_NA IAID:16842752 T1:0 T2:0 (IA_ADDR 1234:5678::4 pltime:18000 vltime:28800)) (client-ID hwaddr/time type 1 time 701792102 000001010000) (server-ID hwaddr/time type 1 time 701792110 42d361623810) (Bootfile-URL my-startup-config) (DNS-search-list aristanetworks.com.) (DNS-server 1234:5678::2))
+   12  14:15:34.152941 IP6 (flowlabel 0x03f85, hlim 1, next-header UDP (17) payload length: 126) fe80::200:1ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 request (xid=becafa (vendor-specific-info) (client-ID hwaddr/time type 1 time 701792102 000001010000) (server-ID hwaddr/time type 1 time 701792110 42d361623810) (option-request Bootfile-URL DNS-search-list DNS-server) (elapsed-time 0) (IA_NA IAID:16842752 T1:3600 T2:5400 (IA_ADDR 1234:5678::4 pltime:7200 vltime:7500)))
+   13  14:15:34.156427 IP6 (flowlabel 0x1570c, hlim 64, next-header UDP (17) payload length: 157) fe80::40d3:61ff:fe62:3810.547 > fe80::200:1ff:fe01:0.546: [udp sum ok] dhcp6 reply (xid=becafa (IA_NA IAID:16842752 T1:0 T2:0 (IA_ADDR 1234:5678::4 pltime:7200 vltime:28800)) (client-ID hwaddr/time type 1 time 701792102 000001010000) (server-ID hwaddr/time type 1 time 701792110 42d361623810) (Bootfile-URL my-startup-config) (DNS-search-list aristanetworks.com.) (DNS-server 1234:5678::2))
+   14  08:08:32.009292 IP6 (flowlabel 0x09903, hlim 1, next-header UDP (17) payload length: 138) fe80::200:44ff:fe01:0.546 > ff02::1:2.547: [udp sum ok] dhcp6 inf-req (xid=b5fcf (vendor-specific-info) (client-ID hwaddr type 1 000044010000) (option-request Bootfile-URL DNS-search-list DNS-server) (elapsed-time 331) (user-class Arista;Test-Dhcpv6Discover;4.21.XX))
diff --git a/tests/dhcpv4v6-rfc5970-rfc8572.pcap b/tests/dhcpv4v6-rfc5970-rfc8572.pcap
new file mode 100644
index 00000000..e4937d07
--- /dev/null
+++ b/tests/dhcpv4v6-rfc5970-rfc8572.pcap